Bryson DeChambeau’s thrilling victory over Rory McIlroy at the U.S. Open last weekend at Pinehurst enthralled golf fans. It’s also the worst thing to happen to the PGA Tour as it heads to Cromwell, Connecticut, this weekend for the Travelers Championship.

Mr. DeChambeau is a member of LIV Golf, the rival tour that has used the deep financial resources of Saudi Arabia’s Public Investment Fund to lure prominent stars from the PGA Tour. While talks of a potential merger continue, the PGA Tour struggles with dwindling television ratings and fan interest.

The Travelers, a popular stop on the PGA Tour, normally benefits from the excitement generated at the U.S. Open. But this year’s U.S. Open fallout isn’t good for the Travelers or the PGA Tour.

Mr. DeChambeau is the brightest star in golf and raised the profile of LIV Golf with his dynamic performance at Pinehurst. Meanwhile, Mr. McIlroy, the no. 2-ranked player in the world, withdrew from the Travelers after announcing he is taking a hiatus from the sport to recover from blowing a chance to win his first major in 10 years.

Bogeys on three of the last four holes, including missed par putts within five feet on holes no. 16 and 18, caused the four-time major winner to lose by one stroke to Mr. DeChambeau, who claimed his second U.S. Open after winning at Winged Foot in 2020. His fan-friendly approach resonated with those in the gallery and millions watching television.

After appearances on “The Tonight Show Starring Jimmy Fallon,” “The Today Show,” “The Pat McAfee Show,” and CNBC, Mr. DeChambeau felt like a conquering hero when he arrived this week at Nashville, where LIV Golf is staging its ninth event of the year. “Having the support of everybody, all the staff and the volunteers, the clubhouse employees, you name it, just everybody, the full-blown support, walking out of that and raising the trophy, it’s truly for LIV and what they’ve done for me,” Mr. DeChambeau said Wednesday.

Someone told him Google searches for his name went up by 250 percent, and he gained 150,000 followers across his social media platform. Tickets to follow his Crushers team during LIV’s Nashville tournament are nearly sold out.

“I’ve got to just say I’m humbled by all of it,” Mr. DeChambeau said. “I never would have thought that from a year and a half ago, things would be where they’re at right now.”

Meanwhile, Mr. McIlroy pulled out of the Travelers at TPC River Highlands and won’t play in the Rocket Mortgage Classic at Detroit or the John Deere Classic at the TPC Deere Run outside Chicago. He announced his next events would be the Genesis Scottish Open and The Open at Royal Troon.

The Travelers, a PGA Tour signature event, is boasting a lineup that includes 49 of the top 50-ranked players in the world, but, of course, does not include Mr. DeChambeau and other members of LIV Golf like Jon Rahm, Brooks Keopka, and Cam Smith, all major champions.

The Travelers includes the world no. 1, Scottie Scheffler, the 2024 PGA Championship winner, Xander Schauffele, the 2023 U.S. Open winner, Wyndham Clark, and a Fed Ex Cup champion, Viktor Hovland. Yet there is no carry-over buzz from the U.S. Open.

Mr. Scheffler, the reigning Masters champion and winner of five tournaments this year, was never a factor at Pinehurst and finished T41. A more competitive Mr. Schauffele tied for seventh, but neither participated in the final day fireworks. “I didn’t really feel like I had a chance to win the tournament at any point,” Mr. Schauffele told reporters in Connecticut.

With Mr. Scheffler dominating the PGA Tour for much of this season, golf needed a rival to add spice to the sport. That might apply when PGA Tour players and LIV golfers merge at The Open, but that doesn’t help the PGA Tour in the short term.

If Mr. McIlroy were at Cromwell as planned, he would attract attention from the media and fans. Instead, the U.S. Open hangover is a headache for the Travelers and the PGA Tour.

The “Bryson Effect” will attract more eyeballs to LIV Golf when the Nashville tournament begins Friday.  He’s already more personable and entertaining than anyone on the PGA Tour, and at age 30 connects with a younger audience through social media and YouTube videos.

“You’re going to see some really cool changes over the next couple of years in regards to LIV,” Mr. DeChambeau said. “I’m not going to give too much away, but there’s a really cool mission and belief that we have in what we’re going to do and what we’re going to accomplish for the game. There’s some awesome stuff coming.”

That’s the last thing the PGA Tour needed.